Dear hwloc users, I have some questions about thread core affinity managed by hwloc.
1) A simple hwloc-hello.c program in the manual on my machine give me the follow results: *** Objects at level 0 Index 0: Machine#0(47GB) *** Objects at level 1 Index 0: NUMANode#0(24GB) Index 1: NUMANode#1(24GB) *** Objects at level 2 Index 0: Socket#0 Index 1: Socket#1 *** Objects at level 3 Index 0: L3(12MB) Index 1: L3(12MB) *** Objects at level 4 Index 0: L2(256KB) Index 1: L2(256KB) Index 2: L2(256KB) Index 3: L2(256KB) Index 4: L2(256KB) Index 5: L2(256KB) Index 6: L2(256KB) Index 7: L2(256KB) Index 8: L2(256KB) Index 9: L2(256KB) Index 10: L2(256KB) Index 11: L2(256KB) *** Objects at level 5 Index 0: L1(32KB) Index 1: L1(32KB) Index 2: L1(32KB) Index 3: L1(32KB) Index 4: L1(32KB) Index 5: L1(32KB) Index 6: L1(32KB) Index 7: L1(32KB) Index 8: L1(32KB) Index 9: L1(32KB) Index 10: L1(32KB) Index 11: L1(32KB) *** Objects at level 6 Index 0: Core#0 Index 1: Core#1 Index 2: Core#2 Index 3: Core#8 Index 4: Core#9 Index 5: Core#10 Index 6: Core#0 Index 7: Core#1 Index 8: Core#2 Index 9: Core#8 Index 10: Core#9 Index 11: Core#10 *** Objects at level 7 Index 0: PU#0 Index 1: PU#1 Index 2: PU#2 Index 3: PU#3 Index 4: PU#4 Index 5: PU#5 Index 6: PU#6 Index 7: PU#7 Index 8: PU#8 Index 9: PU#9 Index 10: PU#10 Index 11: PU#11 I'm so confused. I see couples of cores with the same core id! ( Core#8 for example) How is it possible? 2) logical Core id and Physical core id maybe differents. If i want to be sure that id 0 and id 1 are physically near, i have to use core id or PU id? PU ids are ever physically near? 3) Binding a thread on a core, what's the difference between hwloc_set_cpubind() and hwloc_set_thread_cpubind()? More in depth, my code example works well with: hwloc_set_cpubind(topology, set, HWLOC_CPUBIND_THREAD); and crash with: hwloc_set_thread_cpubind(topology, tid, set, HWLOC_CPUBIND_THREAD); Thanks in forward. -- Ing. Gabriele Fatigati Parallel programmer CINECA Systems & Tecnologies Department Supercomputing Group Via Magnanelli 6/3, Casalecchio di Reno (BO) Italy www.cineca.it Tel: +39 051 6171722 g.fatigati [AT] cineca.it
